DESCRIPTION:(adapted from applicant's abstract) This research seeks to define the neuronal and synaptic plasticity in selected somatosensory and motor systems of the macaque monkey following experimental manipulations that serve as models for normal function of the human nervous system and altered function following disease or injury. Tow specific neural networks will be the focus of the studies: 1) The somatosensory thalamus following acute and chronic spinal cord lesions that involve afferent systems known to be damaged in central pain states in humans as a result of spinal cord injury and, 2) The inferior olivary nuclear complex (IO) of normal macaques, in which we will determine the synaptic organization of major afferent systems to the IO, and whether that organization is altered in the rostral dorsal accessory olive (rDAO) in animals following lesions of the afferent projections from either the spinal cord or the dorsal column nuclei. The olivo-cerebellar system is believed to participate in the learning and timing of movements in animals and in humans. The overall goal is the understanding of the changes that occur following injury, so that new methods of therapy can be developed to address these changes.